Preheat oven to 425°F. Remove the giblets, rinse the chicken inside and out, and pat dry. Salt and pepper the inside of the chicken. Stuff the cavity with the lemon, 1/2 the bunch of rosemary, and garlic. Tie the legs together with a kitchen string and place the chicken, breast side up, in a roasting pan.
Rub the outside of the chicken with the olive oil. Sprinkle with sea salt and black pepper. Throw the rest of the sprigs of rosemary in the pan around the chicken. Roast the chicken for 1 hour or until the juices run clear when you cut between the leg and thigh. Cover the chicken with foil as it cools for 10 minutes. Slice and serve.